Giải thích các bước giải:
Bài 2:
1) `2/3 x - 1/2 = 1/10`
`<=> 2/3 x = 1/10 + 1/2`
`<=> 2/3 x = 3/5`
`<=> x = 3/5 : 2/3`
`<=> x = 9/10`
Vậy `x = 9/10`
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2) `(3 1/2 + 2x) : 3/14 = 7/12`
`<=> 7/2 + 2x = 7/12 . 3/14`
`<=> 7/2 + 2x = 1/8`
`<=> 2x = 1/8 - 7/2`
`<=> 2 x = (-27)/8`
`<=> x = (-27)/16`
Vậy `x =-27/16`
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3) `1/4 + 1/3 : (3x) = -5`
`<=> 1/3 : (3x) = -5 - 1/4`
`<=> 1/3 : (3x) = (-21)/4`
`<=> 3x = 1/3 : (-21)/4`
`<=> 3x = (-4)/63`
`<=> x = (-4)/189`
Vậy `x = -4/189`
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4) `(x + 1/5)^2 + 17/25 = 26/25`
`<=> (x + 1/5)^2 = 26/25 -17/25`
`<=> (x + 1/5)^2 = 9/25`
`<=> (x + 1/5)^2 = (± 3/5)^2`
\(\Leftrightarrow\left[ \begin{array}{l}x + \dfrac{1}{5}=\dfrac{3}{5}\\x + \dfrac{1}{5}=\dfrac{-3}{5}\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}x =\dfrac{2}{5}\\x = \dfrac{-4}{5}\end{array} \right.\)
Vậy `x ∈ {2/5; (-4)/5}`
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5) `(2 1/4 - 1 4/5) x - 3/20 = 1`
`<=> (9/4 - 9/5)x = 1 + 3/20`
`<=> 9/20 x = 23/20`
`<=> x = 23/20 : 9/20`
`<=> x = 23/9`
Vậy `x=23/9`
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6) `(x + 1/2)(2/3 - 2x) = 0`
\(\Leftrightarrow \left[ \begin{array}{l}x + \dfrac{1}{2}=0\\\dfrac{2}{3}-2x=0\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}x=\dfrac{-1}{2}\\x=\dfrac{1}{3}\end{array} \right.\)
Vậy `x ∈ {(-1)/2; 1/3}`
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7) `17/2 - |2x - 3/4| = - 7/4`
`<=> |2x - 3/4| = 17/2 - (-7/4)`
`<=> |2x -3/4| = 41/4`
\(\Leftrightarrow \left[ \begin{array}{l}2x-\dfrac{3}{4}=\dfrac{41}{4}\\2x-\dfrac{3}{4}=\dfrac{-41}{4}\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}2x=11\\2x=\dfrac{-19}{2}\end{array} \right.\Leftrightarrow \left[ \begin{array}{l}x=\dfrac{11}{2}\\x=\dfrac{-19}{4}\end{array} \right.\)
Vậy `x ∈ {11/2; (-19)/4}`
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